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From 1995 to 2001 we conducted several surveys of earthworm populations in 7 land use systems, of varying intensity of disturbance, in Central, Southern and Eastern Uruguay. We evaluated the presence and density of various earthworm genera and species in selected land use systems. Most species found were exotic, belonging to the Lumbricidae (6 species) and Megascolecidae (1 species) families. We found only two native species, one ocnerodrilid and one acanthodrilid. Lumbricids were generally in disturbed agroecosystems, although native species were also found in some disturbed sites. Eukerria sp. had a mean density of 196 ind./m2 in a rice field. The apple orchard, Eucalyptus sp. plantation and natural prairie showed maximum mean densities of 102 ind./m2, 733 ind./m2 and 317 ind./m2, respectively. Our results show the great adaptability of lumbricids to various levels of disturbance and suggest the possibility of a large incidence of exotic worm species in Uruguayan soils.

A series of mutants of human IL-1 receptor antagonist (IL-1ra) has been designed by comparison of IL-1ra and IL-1beta structures in order to increase receptor antagonist capacity. Upon in vitro and in vivo assay of IL-1 antagonism, the IL-1ra mutants DoB 0039 (N91-->R), DoB 0040 (T109-->A) and DoB 0041 (N91/T109-->R/A) could inhibit IL-1beta effects more efficiently than wild-type IL-1ra, with DoB 0041 being the most active. Analysis of the receptor-binding capacity of the IL-1ra mutants showed that all three mutants could inhibit binding of IL-1alpha or IL-1beta to IL-1RI-bearing cells more efficiently than wild-type IL-1ra. Conversely, binding of IL-1beta to IL-1RII-bearing cells could be inhibited by DoB 0041 much less efficiently than by wild-type IL-1ra. It is known that the two types of IL-1 receptors (IL-1RI and IL-1RII) play different roles in the regulation of IL-1 activity, with IL-1RI being solely responsible for cell triggering upon IL-1 binding, whereas IL-1RII acts as a scavenger of IL-1 and can thus be considered as a natural IL-1 inhibitor. Thus, the enhanced inhibitory capacity of DoB 0041 as compared with wild-type IL-1ra is explained in terms of better binding to the activating receptor IL-1RI and poorer interaction with the inhibitory receptor IL-1RII.

Upon structure comparison between IL-1 beta and its antagonist IL-1ra, single or multiple residues along the IL-1 beta sequence were replaced with the corresponding amino acids present in the IL-1ra protein, in the attempt to identify sites important for receptor binding and for biologic activity on the two molecules. Ten of fifteen mutant proteins had activity comparable to that of wild-type IL-1 beta in three different biologic assays and in receptor binding, indicating that the introduced changes did not influence the functional structure of the protein. Conversely, three mutants (SMIL-9: 127/263 R/T-->W/Y; SMIL-10: 125/127/263/265 T/R/T/Q-->R/W/Y/E; SMIL-15:222/227 I/E-->S/S) showed an increased binding capacity for IL-1RI, not paralleled by increased agonist activity, indicating that the introduced IL-1ra residues could be involved in the nonagonist IL-1RI binding site. On the other hand, two mutants showed diminished binding capacity with concomitant decrease in biologic activity. Both mutants (SMIL-1, five substitutions in the loop 202-214; and SMIL-3, total replacement of the loop 164-173 with the IL-1ra stretch 52-55) included substitutions of residues allegedly important for agonist binding to IL-1RI. Mutant SMIL-3 showed the most profound reduction in binding capacity for IL-1RI (CDw121a) and a more than 1,000-fold reduced biologic activity both in vitro and in vivo, but it retained full capacity of binding to IL-1RII (CDw121b) and acted as a selective antagonist of IL-1RII. From these results the following conclusions can be drawn. IL-1 beta binds to IL-1RI and to IL-1RII through different sites, and the loop 164-173 appears as one of the areas involved in the selective interaction with IL-1RI. Agonist (IL-1 beta) and nonagonist (IL-1ra) binding to IL-1RI occur through distinct sites, with loops 164-173 and 202-214 of IL-1 beta identified as two of the sites selectively involved in agonist binding to the activating receptor.

The aim of this study was to apply an easy method for the quantitative evaluation of changes in myocardial fibrocell size (area, diameter, circular shape factor, nuclear area, DNA content), and in the fibrous-interstitial area in hypertrophic cardiomyopathy (HCM) by mean of a computerized image analysis. A Vidas image analyser was employed for the morphometric study. The following parameters were assessed: area, maximum and minimum diameters, circular shape factor of myocytes; percentage of fibrosis; DNA content (integrated optical density) nuclear area of myocytes. The morphometric results in HCM compared to the ones in normal hearts, indicate an increase in the myocyte area and the transverse diameters, especially in the septum and left ventricle, altogether illustrating the hypertrophic condition of the myocytes, and increased fibrotic area was found in the left ventricular wall and septum (22.6 +/- 2.1% and 15.9 +/- 2.9% respectively). Densitometric analysis showed a significant increase in all test samples then compared with controls. The increase in the two nuclear parameters (area and DNA) also suggests hyperplasia. It is concluded that the morphometric determination of the morphologic abnormalities occurring in HCM by a rapid and less laborious approach, is an extremely useful method to describe the characteristics of this pathologic condition.